Devices, whereby a securing of the femoral head against rotation is attempted by a single hip screw, i.e. a longitudinal bone fixing means, are already known. A device is known, for example, from EP-B 0 441 577, that has a sleeve accommodating the hip screw in a sliding manner, while the sleeve can be secured against rotation in the intramedullary pin by a locking screw proximally introduced into the intramedullary pin. The shaft of the hip screw and the bore of the sleeve are, however, not circular, so that the hip screw cannot rotate in the sleeve. However, during the introduction into the head of the femur the hip screw has to be able to rotate. For this reason during implantation the hip screw has to be inserted first and the sliding sleeve only afterwards. The two elements cannot be introduced together, so that the operation will be a complicated one. There is further the danger, that the hip screw would move medially when a compression screw is not additionally employed. A further disadvantage is, that the locking screw has to introduced from above (cranially) into the intramedullary pin, representing a further operating procedure. Finally, in the case of a potential subsequent removal of the hip screw, a relatively substantial intervention is required to release the locking screw, screwed proximally into the intramedullary pin, in a step prior to removing the hip screw.
Furthermore, from U.S. Pat. No. 5,454,813 Lawes, an intramedullary pin with a hip screw and a sliding sleeve is known, wherein the transition in the intramedullary pin, the external and internal section of the sliding sleeve and the shaft of the hip screw have a non-circular construction. Consequently, the sliding sleeve acts as an anti-rotational means between the hip screw and the intramedullary pin. This known device has the same disadvantages as EP-B 0 441 577, i.e. a complicated operating technique, both during the implanting and removal of the hip screw and the medial movement can be prevented only with an additional component (tension adjuster).
The purpose of the preceding discussion of the state-of-the-art is merely to explain the field of the invention and does not mean that the state-of-the-art quoted has actually been published or is public knowledge at the time of this application.
This is where the invention wants to provide remedy. The invention is based on the problem to produce a device for the treatment of femoral fractures, particularly of proximal femoral fractures, that allows a simple and reliable blocking of the rotation between the longitudinal bone fixing element (e.g. a hip screw) and the intramedullary pin, simplifies and shortens the operating procedure and does not limit the lateral sliding of the longitudinal bone fixing element.